DE2737561A1 - DEVICE FOR AUTOMOTIVE CORRECT SCANNING OF THE TRACKS OF A RECORDING MEDIA SIDE OF THE MAGNETIC HEAD IN VIDEO TAPE RECORDER - Google Patents

Description

Dipl.-Ing. H. MITSCHERLICH Dipl. In ₉ . K. GUNSCHMANN

Dr. rer. not. W. KÖRBER

Dipl. Ing. J. SCHMIDT-EVERS

PATENT LAWYERS

D -8000 MÖNCHEN 22 S'einsdorfstraßelO

'S * (089) * 29 66 84

V). Au

2 7 3 7 b b

VJ77

SONY CORPORATION 7-35 Kitashinagawa 6-Chome, Shinagawa-ku

Tokyo / Japan

Patent application

Device for automatic correct scanning of the tracks of a recording medium by the Magnetic head in video tape recorders

8f ^:: '08 / 1034

2 '/ j 7 b

The present invention relates generally to playback system, and more particularly to a playback system with a device for automatic correct scanning of the tracks of a recording medium on the part of the magnetic head in video tape recorders.

In general, in a video tape recorder, a video signal or composite signal is recorded on a magnetic tape recorded as a plurality of recording tracks, which extend in the longitudinal direction of the belt and are parallel to one another, wherein there is a predetermined distance between the adjacent tracks.

In order to achieve a high recording density in such a video tape recorder, it is necessary the pitch or pitch of the recording tracks and the width of each recording track to make it narrower. In such a case and if the rotational speed is one rotatable magnetic head is selected to be the same as that in an ordinary video tape recorder, so the tape transport speed can be made low. Thus, it becomes a long-term record possible. In the case where the tape transport speed is selected so that it is the same as that of the ordinary video tape recorder if the rotating speed of the rotatable one Magnetic head is made high, wide frequency signals can be recorded. In this case, even if the width of the recording tracks is made narrow, due to the fact that

8 IJ 't H Π 8/1 0 3 4

I / j '·' over i

the relationship between the signal and the noise, i.e. the signal-to-noise ratio deteriorates less is, the quality of the reproduced signals as a whole can be made high.

The recording tracks made by the rotatable Magnetic heads are, in reality, always straight, with the linearity of the recording tracks is worsened by the distortion of the tape, which is caused by, for example, stretching of the tape and the like. Is effected. When such recording tracks by the rotatable magnetic head are scanned, a so-called tracking error occurs, so that the level of the reproduced signals changed v / ird. This error becomes more and more noticeable as the track becomes narrower.

If the track width of the reproducing head is made larger than that of the recording head, then therefore, the above error can be eliminated. In this case, however, there may be a risk that a signal from an adjacent track is reproduced, whereby the quality of the reproduced Signals, in turn, is deteriorated.

For this reason, a method has been proposed by which the rotary magnetic head by an electromechanical transducer in a direction for cutting the longitudinal direction of the tape Carrying out an automatic scanning of the tracks on the part of the magnetic head is moved. After this

8 0! η η pt I 1 0 3 ORIGINAL INSPECTED

2 7 3 7 b b

Method, a tracking error signal is generated in which the magnetic head with the transducer by a small amount is "intentionally deflected" sinusoidally in each direction from the track center point, thus creating a To obtain carrier amplitude modulation of a known frequency and phase. This tracking error signal is fed back to the converter to a tracking servo loop to obtain. Even if the recording tracks are curved, accordingly, the reproducing head can scan the recording tracks. According to this procedure however, the carrier amplitude modulation is always generated in a reproduced signal, so that the Phase of the reproduced signal is thereby changed, in particular a phase error of a chrominance signal caused. In addition, the device has to carry out the above procedure a complicated construction.

Accordingly, the object of the present invention is to provide a display system with a device for automatic correct scanning of the tracks of a recording medium by the magnetic head on video tape recorders, which means that a reproduced signal is less affected.

The object of the present invention is also to provide a reproducing device which uses is used to reproduce the recording of a magnetic tape on which the signals in high Density are recorded.

809808/1034

ORIGINAL INSPECTED

2 7 3 7 b b i

Another object of the present invention is to provide an improved recording system with an improved device for automatic correct scanning of the tracks of a recording medium on the part of the magnetic head in video tape recorders, which is based on the fact that the Shapes of the recording tracks in the longitudinal direction are not so different from each other and that the shapes of the recording tracks formed in the vicinity are substantially the same.

According to one aspect of the invention, the intentional Deflection of a magnetic head carried out only in one direction from the center of the track, whereby an error signal is obtained in which a reproduced signal when the head is deflected and a Signal can be compared if the head is not deflected, whereupon the error signal is stored and a transducer for head deflection driven by the same error signal in a constant period will.

The subject of the invention is a playback device with a rotatable magnetic head, which scans video tracks recorded on a magnetic tape, with a head deflector for Moving the rotatable magnetic head and having a control circuit for supplying a control signal the head deflector so that the rotatable magnetic head scans a center point of the video tracks. That Control signal is generated by using one of the reproduced signals from the rotating magnetic head is compared to the other of the same if the

809808/1034

ORIGINAL

2 V 3 7 b b

Head deflector moved a predetermined distance will.

Other objects, features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings; show in it:

Figure 1A is plan view of examples of patterns and 1B: or images of recording tracks on magnetic tapes;

Figure 2 is a cross-sectional view of an example of a rotary magnetic head assembly a video tape recorder in which the present subject matter Applies;

Figure 3: a block diagram of a circuit of the video tape recorder in which the present invention finds application;

Figure 4A
up to 4K:

Waveform pictures to explain the

video tape recorder shown in Figure 3;

and

FIG. 5A waveform images which are similar to those according to FIGS. 4A to 4K, however, differ therefrom in terms of the position of the recording tracks.

8 D H «fl R / 1034

2 V 3 '/ b b I

The description of preferred embodiments now follows. FIGS. 1A and 1B are top views of FIG Magnetic tapes on which various track patterns are formed by a known video tape recorder. As shown in Figures 1A and IB, the track pattern is generally curved upwards or downwards. Accordingly, if a magnetic tape on which the track pattern as shown in Fig. 1A is formed by one video tape recorder, by another Video tape recorder having a magnetic head capable of scanning as shown in Figure 1B performs, the level of a reproduced signal is determined according to the position of the Head changed. As a result, a phase error is caused in the reproduced signal, in particular in the case of reproducing a color video signal, the color reproduction is deteriorated.

The track pattern is changed or changed a lot depending on the video tape recorder, when a video tape recorder is exchanged for a different video tape recorder, where however, if the same VTR for both signal recording and reproduction is used, the recorded and scanned images do not change very much. The present invention is based on the above fact.

An example of the present invention will be described below with reference to the drawings. FIG. 2 is a cross-sectional view of an example of a rotary magnetic head assembly 1

80 9 808/1034 ORIGINAL INSPECTED

2 V J 7 b b

a video tape recorder to which the present invention is applicable. The rotary magnetic head assembly

I has a fixed lower drum 2, a rotatable one upper drum 3, a rotary shaft 4 and a servo motor 5 for driving the rotary shaft 4. In one predetermined portion of the lower surface of the upper drum 3, head deflector members 10 are such arranged so that their longitudinal directions coincide with the diameter of the rotatable upper drum 3 and its shifting or moving direction is an upward and downward direction. One end to each Head deflector element 10 near the rotating shaft 4 is mounted on the upper drum 3, the other end of each element 10 with a magnetic head

II is attached so that the front end or the The tip of the head 11 extends slightly over the outer circumferential surface the drum 3 also extends. Each head deflector element 10 could be an electromechanical one Be transducers, such as a piezoelectric plate, piezoceramic plate, two-element plate, which consists of the above two plates joined together, or the like.

The head deflector element 10 is supplied with control voltage from an input terminal 6 through a slip ring 7 provided around the rotating shaft 4, for example, and in the upward or downward direction is bent so that the scanning position of the head 11 is shifted up or down. An output power from the head 11 is provided by a rotatable transformer 8, for example supplied, which is arranged around the rotating shaft 4 around,

809 8 0 8/1034

ORIGINAL INSPECTED

namely the output terminals 9.

Magnetic tape T (Figure 3) is around the outer circumference of the head assembly 1 with an angular range of approximately 180 ° wrapped around and transported at a predetermined speed. The heads 11 are with fed a video signal whose brightness signal, for example, frequency-modulated and whose chrominance signal is converted to a low-band component, the video signal being recorded on the tape is that each field of the same forms an oblique magnetic track. The video signal is also reproduced from the tracks.

Figure 3 is a circuit diagram of the video tape recorder to which the present invention is applied. In this video tape recorder, the input terminal 100 is in the recording mode applied video signal through a recording circuit 101 and a recording contact R of a recording-reproduction switch 102 fed to the heads 11. At this point there will be a switch 103, which is used to supply a control voltage to the head deflector elements 10, is switched off, so that no control circuit is applied to the head deflector elements 10. So the heads feel 11 the tape T at predetermined positions to magnetic tracks to educate on it.

In the reproducing mode, the signal reproduced by the head 11 is transmitted through a reproducing contact P of the switch 102 and a head amplifier 12 are applied to a reproduction circuit 13,

803808/1034 ORIGINAL INSPECTB)

')' J ', ι l · i

ί ι .j ■■ ..; U ι

- 12 -

which has an FII demodulator and so on. That demodulated Video signal from the reproducing circuit 13 becomes an output terminal 14 and the RF signal out the head amplifier 12 is supplied to an envelope detector circuit 15. The signal detected by the detector the envelope detector circuit 15 becomes control circuits or circuits 16 and 17 of the interrogation memory circuits 1S or 19 supplied. The output signals from the interrogation memory circuits 18 and 19 become one Processing circuit or conditioning circuit 20 supplied, the output signal through a switching circuit 21 is fed to an interrogation memory circuit 22. In this case, everyone feels or asks Interrogation memory circuits 18, 19 and 22 receive the input pulses by interrogation pulses which are supplied to them and stores the peak values of all sampled or interrogated signals. From each of the Polling memory circuits can also sequentially store the contents by the sampling pulse can be read out until a new input signal is applied to it. In this example such a circuit which has no memory function is used as the query memory circuit 19 will.

The signal from the interrogation memory circuit 22 is passed through a circuit 23, a memory circuit 24, an amplifier 25, an adder circuit 26 and a switch 103 connect the head deflectors 10 of the Rotary magnetic head assembly 1 is supplied as a control signal V. As the memory circuit 24, a circuit used, which the applied signal from the

8 0 ° - N η 8/1 Q 3 L

ORIGINAL INSPECTED

I ι ό, ϋ b

Interrogation memory circuit 22 through the circuit

23 stores, the stored signal reads out according to the query pulse and the read out therefrom Delivers the signal as an integrated signal.

The signal from the adding circuit 26 is fed through an amplifier 27 to the conditioning circuit 20. A desired DC voltage V from a voltage source 28 is set by a switching circuit 29 and an amplifier 30 are applied to the adding circuit 26. The signal from the playback circuit or Jem demodulator 13 is also a synchronous separation circuit 31 supplied. The horizontal sync signal from the sync separation circuit 31 becomes a Inquiry signal generator or scanning signal generator 32 fed. The reason why the horizontal sync signal is derived is that there is the The level of the synchro peak in the recorded signals is always constant, a tracking error of the heads 11 can be known during playback by comparing the level of the sync peak. Of the Sampling or interrogation pulse from the interrogation signal 32 is obtained, the query memory circuits 18, 19, 22 and the memory circuit

24 supplied.

The vertical synchronization signal from the synchronous separation circuit 31 is fed to a switching signal generator 33, which generate a switching signal. The switching signal from the switching signal generator 33 is sent to the control circuits or circuits 16, 17, 21 and 29, respectively.

8 0 ^f i 3 η 8/1 0 3 U ORIGINAL INSPECTED

The servo-locked or rigid signal from the servo circuit 34 is fed to the switching signal generator 33. The servo-locked signal is a signal indicating, for example, that the drum servo is operating works normally.

The mode of operation of the circuit shown in FIG. 3 will now be explained with reference to FIGS. 4A to 4K. In Figure 4K, the whole lines are lines that draw the track images or track patterns on the tape T continuously. Ie the
Distance or the distance between the full lines in Figure 4A represents the track width. For example, if the head deflector elements 10 are not supplied with the control signal, ie the output signal of the adder circuit 26, the heads 11 can read the tape T along the dashed lines in Figure 4A scan during the first field. The above case will now be described. When the switching signal generator 33 is fed with the servo-locked signal S (FIG. 4D) from the servo circuit 34 and with the vertical synchronization signal D (FIG. 4C) from the synchronous separation circuit 31, the switching signal generator generates switching signals S ₁ , S ~ and S-. (Figure 4E, Figure 4G and 4J) consecutively. The switching circuit 29 is switched on by the switching signal S ~, so that at this point in time a predetermined direct current voltage V
from the voltage source 28 to the adding circuit
26 is applied so that a predetermined DC voltage V from the adding circuit 26 to the
Head deflector elements 10 is applied. The heads 11 can accordingly follow the track pattern along the

8 0 9 3 0 8/1034
ORIGINAL IMW

- 15 -

scan dashed lines in Figure 4A during the first and second parts of the image. During the first field, the switching signal S _{1 is} fed to the circuit 16, so that the signal with the envelope shown in FIG. 4B is fed from the detector 15 through the circuit 16 to the interrogation memory circuit 18. The interrogation signal generator 32 in the meantime generates the interrogation pulse P, which corresponds to each horizontal sync peak period of the signal S and is fed to the interrogation memory circuit 18. The envelope signal of the signal S is thus interrogated or sampled by the interrogation memory circuit 18 and then stored therein as the sampled or interrogated value according to FIG. 4F. In Figure 4F, the vertical or longitudinal lines represent the queried values.

The switching signal generator 33 soon generates the switching signal S ~, which during the second field corresponds to this period according to FIG. 4G. The switching signal S "is fed to the switching circuit 17, 21 or 29, to turn on these circuits accordingly. The predetermined voltage V is applied to the head deflector elements 10 correspondingly fed with the result that the heads 11 along the tape T, for example scan the dashed lines according to Figure 4A. The reproduced signal from the mind 11, which are moved, is fed through the circuit to the interrogation memory circuit 19, which is fed with an interrogation signal from the interrogation signal generator 32, so that the interrogated or scanned Fourth of the envelope signal of the signal S in

8 0 <> ■? ■ ι) κ / 1 0 3 4 INSPECTED

2'ί'ό

Query storage circuit 19 is ^{stored in accordance with I 1} IgUr 411. In this case, at the point in time at which the first interrogation or sampling is carried out, a level V.

a ι

sample in the first field in the interrogation memory circuit 18 stored and then read out therefrom and then fed to the processing circuit 20 which is also with the control signal or the DC voltage V from the adding circuit 26 is fed. Thus, the subsequent process in the editing or processing circuit 20 becomes achieved.

^V d1 ^{= V} a1 - ^V b1 - ^V c

Where V, is a signal corresponding to an effect, which is applied to the reproduced output power when a control signal V is on the head deflector element 10 is applied, where it is expressed by V, - f (V, S) and S as

C S III ITl

described below. In the second part of the picture is

S zero. The processed result V ,, then becomes m ^ d1

fed through the circuit 21 to the interrogation memory circuit 22 to be stored therein. A similar process is then performed during each sync spike period in the second field, with the edited or processed results V,, V, V,., ... being stored in the interrogation memory circuit 22 in that order. In the query memory device 22 is accordingly a signal S _r

8 0 ';'π ρ / 1 0 3 U

ORIGINAL INSPECTED

stored, the level of which corresponds to the shift amount between the heads 11 and the tracks is changed as shown in FIG.

During the third part, that is shown in FIG. 4J Switching signal S shown from the switching signal jober 33 fed to the circuit 23 to turn it on. The result is the signal S from the interrogation memory circuit 22 fed through the circuit 23 of the memory circuit 24, which a voltage signal S generates that shown in Figure 4K. This signal S is through amplifier 25 and the adding circuit 26 the head deflector elements 10 as Control signal V for moving the heads 11 is supplied in such a way that that they are moved up and down along tracks that are twisted in a zigzag line are. The first correction process is thus ended.

The second correction process is carried out in the fourth through sixth partial images achieved. Since the head deflector elements with the control signal V during the first Correction process have been fed, if the track pattern is the same as that the previous device according to Figure 4A, the heads 11 the track pattern during the fourth field scan correctly. A sampled or interrogated signal is thus used during the fourth field at a constant level in the interrogation memory circuit 18 stored in accordance with Figure 4F. During the fifth field, the control signal V, which is formed by the signal S from the memory circuit 24 of the DC voltage V from the

8 0? :. {■ ·; 8/1 Π 3 L ORIGINAL INSPECTED

Z ί J '-J * i

Voltage source 28 is added to the head deflector elements 10 so that the heads 11 achieve S [HIr, as shown in Figure 4A. The sampled signal having a constant level different from that of the sampled signal stored in the interrogation memory circuit 18 is accordingly stored in the interrogation memory circuit 19 as shown in FIG. 4H. The process similar to that previously expressed by the above equation is achieved in the processing circuit 20 so that a sampled signal S having a waveform similar to the previous one is obtained, the Signal is stored in the query storage circuit. This signal S is fed to the memory circuit 24 by the control circuit or switching circuit 23 when the switching signal S_. is applied to the control or switching circuit 23 to turn it on, whereupon the signal is stored in the memory circuit. As a result, the signal S from the memory circuit 24 is supplied to the head deflector elements 10 as the control signal V in the sixth field
To continue the process.

Control signal V supplied to ensure the correct track

Figs. 5A to 5K show the case in which the posture of the recording lines is after the second and the third correction process is changed. That means differentiating between the fourth and sixth sub-images the position of the recording tracks changes from that during the first to the third field, where the position of the recording tracks

8 0: 1308/1034

- .., ORIGINAL INSPECTED

during the seventh to ninth fields are different from those during the first to sixth fields differs, as shown in Figure 5Λ. In this case it can be seen that the control signal V by the same process as described above is generated, so a more detailed description thereof shortly omitted.

The above description is given for the case where the curve of the recording track does not change is. However, even when this curve is changed, it can be seen that the necessary Control signal V is obtained by the same operation.

In the above example, all synchronizing peaks are also measured, but it is possible to use the Reduce the number of synchronizing peaks that are to be measured. I.e. it is sufficient to use the Interrogation or scanning process in the first, middle and last track to at least one track achieve.

In the example above, the envelope signal is also sampled by the sync peaks and then compared, however, the video signals in adjacent tracks have such a correlation, that they can be scanned at a desired pattern. When using an analog memory circuit is, it is also possible that the envelope signals themselves are compared to an error signal to create.

8 0 ^r ). '. .1 a / 1 η 3 L

WSPECTED

Furthermore, it is not necessary to always repeat the above correction process for every third partial image. If it is possible to determine that the correct track has been obtained, then this is sufficient to achieve a correction process for several partial images or several hundred partial images. There in this case, the automatic gain control operation is performed, if the correct track is obtained, the track shift or track shift by about 10-20% has no Effect on the reproduced image. If the correction process is carried out after performing the correct If the trace has been carried out by about 10-20% of the DC bias, then none will be found Flicker or the like. Instead.

If the size of a correction is selected to be less than 10% of the size of a detected Error, furthermore, no image shift is caused, so that the correction is achieved smoothly can be.

With the device according to the invention even a Zigzag track must be scanned correctly. The width of the tracks can accordingly be reduced and thus the Recording density can be increased so that the quality of a reproduced image is increased or a long one Recording and / or playback becomes possible.

In the present invention, a constant or predetermined DC voltage is used to intentionally deflecting the head deflector elements so

8093Ü8 / 103A

ORIGINAL INSPECTED

27 y

that the reproduced signal is not amplitude modulated and thus no phase error is caused in the reproduced signal. Thus, no tone color error is caused even if the invention in the reproduction of a color video signal is used.

The above description has been given of the case where the present invention is applied to a video tape recorder Applies, however, the present invention can also be applied to the case can, in which a video signal, which is recorded for example on a magnetic sheet, is reproduced will.

A bucket brigade device can also be used as the interrogation memory circuit (bucket brigade device), a charge coupled device, a digital storage circuit or the like. Use.

It will be apparent that numerous modifications and variations can be made by those skilled in the art within Protection scope of the appended claims can be carried out.

The patent attorney

8 0 9 3 0 8/1 0 3 A ORIGINAL INSPECTED

Claims (8)

I 7 W 7 h b claims 1., playback system with at least one magnetic head for scanning recording tracks which are mutually related on a recording medium are formed in parallel, a device for deflecting the magnetic head transversely to Longitudinal direction of the tracks and a device for moving the deflection device characterized by a device for Operating the means for moving the deflector (10) intermittently in a predetermined Distance at which the magnetic head (11) scans one of the recording tracks, means for forming a first envelope signal of a reproduced signal the magnetic head (11) when the magnetic head (11) scans one of the recording tracks, means for forming a second envelope signal a reproduced signal from the magnetic head (11) when the magnetic head (11) the another recording track scans, means for comparing the first envelope signal with the second envelope signal for generating an error signal, a device for storing the error signal and a device for supplying a control signal accordingly the stored error signal of the deflection device. 809808/1034 ORIGINAL INSPECTED 2 7 3 7 b b V. » 2. Playback system according to claim 1, characterized by a device (28) for supplying a predetermined DC voltage to the deflector moving means. 3. Playback system according to claim 1, characterized in that the deflection device (10) is an electromechanical transducer. 4. Playback system according to claim 3, characterized in that the ichnet
electromechanical transducer is a piezoelectric plate. 5. Playback system according to claim 3, characterized in that the ichnet
electromechanical transducer is a piezoceramic plate. 6. Playback system according to claim 1, characterized in that the comparator device a signal sampling circuit (18, 19). 7. A playback system according to claim 6, characterized in that the signal sampling circuit samples a signal which is applied to this circuit at least three times during a period when the
said head scans one of the recording tracks. 8 u 9 κ η R / 1 0 3 A ORIGINAL INSPECTED